Absolute records

Ocean temperatures are rising faster and faster

From April 2023 to July 2024, global average sea surface temperatures were higher than ever before.

(Bild: APA/africaimages.com)

According to a study, sea surface temperatures are rising faster and faster: while the increase from 1985 to 1989 was 0.06 degrees Celsius per decade, it was already 0.27 degrees from 2019 to 2023 - more than four times as much.

Until now, a linear increase in this warming was often assumed. However, the study published in the journal "Environmental Research Letters" by Christopher Merchant's group at the University of Reading in England indicates that the temperature rise is accelerating significantly.

From April 2023 to July 2024, global average sea surface temperatures were higher than ever before. This was also due to the intense occurrence of the El Niño climate phenomenon. During El Niño, sea surface temperatures in some parts of the Pacific are significantly higher than usual due to changes in currents in the atmosphere and the oceans.

The way to slow this warming is to turn off the hot tap by reducing global carbon emissions and moving towards net zero.

Christopher Merchant

In the ocean areas between 60 degrees north latitude and 60 degrees south latitude, surface temperatures during this period were up to 0.31 degrees Celsius higher than the maximum values previously measured in the respective seasons. The average was 0.18 degrees.

For these ocean regions - which in the northern hemisphere extend as far as the height of St. Petersburg and in the southern hemisphere as far south as Tierra del Fuego - the researchers used satellite measurement data and various climate models to investigate what proportion of the warming was due to natural phenomena - such as El Niño or increased solar activity - and what proportion was due to man-made global warming.

(Bild: AFP)

Man-made climate change
Between the two strong El Niño events of 2015/2016 and 2023/2024, the peak values of the average sea surface temperature rose by 0.22 degrees. According to the researchers, almost half of this (44 percent) is attributable to man-made climate change - primarily due to the greenhouse gases that have accumulated in the atmosphere.

"Our results provide observational evidence that the global increase in mean sea surface temperature inferred over the last 40 years is likely to be exceeded within the next 20 years," write the study authors. Assuming a linear increase in temperature, the forecasts for the coming years would be significantly too low, they emphasize.

According to the study, the trend in mean sea surface temperature essentially follows the trend in the amount of energy that has accumulated on Earth as a result of the greenhouse effect - through carbon dioxide (CO2) and other greenhouse gases in the atmosphere.

Carbon emissions urgently need to be reduced
In a press release from his university, Merchant compares the rise in sea surface temperatures to filling a bathtub: 40 years ago, the tap with the hot water was only slightly open, but now it is much more. "The way to slow down this warming is to close the hot tap by reducing global carbon emissions and moving towards net zero," emphasizes Merchant.